Three kinds of error, and only one is easy
Checking writing means finding three different things, and they are not equally findable.
Mechanical errors have a right answer. A missing capital, a doubled word, an unclosed bracket, teh for the. A rule catches these reliably and there is nothing to argue about.
Grammatical errors usually have a right answer, but finding them needs the sentence's structure. Subject and verb disagreeing across a long clause, a pronoun with no clear referent, a dangling modifier. Rules catch some of these and miss others, because the same words can be a mistake or a deliberate construction.
Style has no right answer at all. Sentence length, passive voice, adverbs, hedging — these are judgements about audience and register dressed up as rules. A checker that flags them is offering an opinion, and it is worth knowing whose.
The [msm_tool slug="grammar-checker"] separates what it is confident about from what it is merely suggesting, because a tool that presents all three with the same certainty teaches you to ignore all three equally.
The errors checkers invent
False positives are the real cost of automated checking, and they cluster in predictable places.
- Proper nouns and technical terms. Product names, surnames, library names and jargon get flagged as misspellings. Every dismissal trains you to dismiss faster, which is how a real error slips past.
- Deliberate fragments. A one-word sentence for emphasis. Like that. Perfectly good prose, reliably flagged.
- Passive voice with a purpose. The file was deleted is right when you do not know who deleted it, and in scientific writing the passive is the convention rather than a failing.
- Dialect. British, American, Indian and Australian English disagree about spelling, punctuation inside quotation marks, and collective nouns taking singular or plural verbs. None of them is an error.
- Quoted text. A quotation reproduces someone else's words, mistakes included. Correcting it is the one edit you must not make.
The errors checkers miss
More important, because nothing draws your attention to them.
Homophone errors survive almost everything: their for there, its for it's, affect for effect, principal for principle. Each is a correctly spelled English word in a grammatically valid position.
So do factual errors, which no grammar tool claims to catch but which readers do not separate from the rest — a sentence with the wrong date is wrong regardless of how clean the syntax is. So does a paragraph that contradicts the one before it. So does the sentence you wrote twice, three pages apart, in slightly different words.
And the largest miss of all: prose that is fluent, correct and says nothing. There is no rule for that.
How to run a check without breaking your voice
- Fix mechanics first, in one pass. Typos and punctuation are uncontroversial. Clear them before you look at anything requiring judgement.
- Treat every style flag as a question. Not fix this but why did I write it this way? Sometimes the answer is carelessness. Often it is that the sentence needed that shape.
- Refuse the suggestions that flatten you. Shortening every long sentence produces prose with no rhythm. Removing every hedge produces claims you cannot defend.
- Read it aloud at the end. Your ear catches the repeated word, the clause that runs out of breath and the sentence that lands wrong — none of which any checker will mention.
Non-native writers, and a warning
Checkers are genuinely valuable if English is not your first language: article use, preposition choice and verb aspect are exactly where rules help most, and getting them corrected consistently teaches the pattern.
The warning is that the same tools push hard towards a narrow register of English, and applied without resistance they will remove the constructions that made your writing yours. Correctness and homogeneity are not the same goal. Take the corrections and refuse the flattening.
What leaves your browser
Rule-based checking runs entirely on your machine, so a contract, a diagnosis or an unpublished manuscript can be checked without any of it going anywhere. Add an AI key and the text goes from your browser directly to the provider you chose, under their terms — better prose, and a decision worth making deliberately for anything confidential.
Either way this site stores neither the text nor the corrections.